The primary purpose of impedance
audiometry is to determine the status of
the tympanic membrane and middle ear via
tympanometry. The secondary purpose of
this test is to evaluate acoustic reflex
pathways, which include cranial nerves
(CN) VII and VIII and the auditory
brainstem. This test cannot be used to
directly assess auditory sensitivity,
although results are interpreted in
conjunction with other threshold
measures.
Acoustic immittance is a measurement of
energy or air pressure flow, which
involves the ear canal, eardrum,
ossicular chain, tensor tympani,
stapedius muscle, cochlea, CNs VII and
VIII, and the brainstem. Mass, mobility,
and resistance of the outer and middle
ear systems affect this test. The
reciprocal of acoustic immittance is
acoustic impedance. Particularly in
earlier years, these measurements were
performed in impedance rather than
immittance measures; thus, the term
impedance audiometry is sometimes used.
The primary purpose of impedance audiometry is to determine the status of the tympanic membrane and middle ear via tympanometry. The secondary purpose of this test is to evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem.